[Membrane potential levels in Acetabularia mediterranea cells during changes in temperature of the medium]

The transitions of vacuole-medium potential difference (EM) has been revealed between two stable levels: -170 mV at 20 degrees, when EM greatly exceeds K+-equilibrium potential (EK equals -104 MV) due to electrogenic Cl-pump, and -82+/-3mV at the critical cooling temperature 9.0+/-1.3 degrees, when EM is close to EK. The control of electrogenic ion pimping on the tonoplast was shown during periodical cooling-heating cycles.